1
An experimental set up is used whereby the serosal (out)side or mucosal (in)side of the guinea‐pig isolated tracheal tube can be stimulated selectively with drugs and reactivity measured.
2
...Potassium induces a concentration‐dependent (5 − 70 mM) monophasic contraction of tracheal tubes when added on the outside. In contrast, on the inside, potassium induces a concentration‐dependent relaxation at low concentrations (5–40 mM) which was reversed into a contraction up to approximately basal tone at higher concentrations (50–70 mM).
3
Epithelium denudation reversed the potassium‐induced relaxation into a contraction. Interestingly, in the ‘half epithelium‐denuded trachea the contractions were significantly (P<0.01) reduced by 46% compared to complete epithelium‐denuded tissues.
4
Incubation with the nitric oxide (NO) synthase inhibitor NΩ‐nitro‐L‐arginine methyl ester (l‐NAME, 120 μm) for 30 min on the inside of the tracheal tube completely prevented the relaxation. However, L‐NAME did not reverse the potassium‐induced relaxation into a contraction. This indicates that potassium does not penetrate through the epithelial layer.
5
It is concluded that depolarization of smooth muscle cells leads to a monophasic contraction and that depolarization of the epithelium leads to a relaxation of tracheal smooth muscle. The epithelial layer has an important barrier function and can release relaxing factors like NO.
In humans, respiratory viral infections lead to increased airway responsiveness and exacerbations of asthma. In the present study, the role of interleukin-5 (IL-5) in virus-induced airway ...hyperresponsiveness and inflammation was examined in guinea pigs. In animals treated with control antibody, parainfluenza-3 virus significantly potentiated (219%) the histamine-induced increase in lung resistance compared with vehicle treatment. In addition, viral infection significantly increased (130 to 450%) the responsiveness of isolated tracheal segments to histamine in animals treated with control antibody. In guinea pigs treated with control antibody, the numbers of eosinophils (226%), neutrophils (1,380%), and monocytes (626%) in bronchoalveolar lavage fluid were significantly increased after viral infection. The level of major basic protein in bronchoalveolar lavage fluid was not altered after viral infection. In addition, electron microscopic examination of eosinophils in airway tissue and alveolar lumen did not point to increased degranulation after viral infection. In guinea pigs treated with antibody to IL-5 the virus-induced airway hyperresponsiveness to histamine both in vivo and in vitro was almost completely inhibited. In guinea pigs treated with anti-IL-5, viral infection significantly increased the numbers of eosinophils (234%), neutrophils (1,255%), and monocytes (617%) in bronchoalveolar lavage fluid. These data suggest that IL-5 plays an important role in airway hyperresponsiveness to histamine but not in the infiltration of eosinophils after respiratory viral infection.
Hourly metabolic rates, measured as oxygen consumption, were relatively high from 1000 to 2100h compared with 2200 to 0500h forCuetasp., whereasFurgella intermediaexhibited a peak in the afternoon, ...from 1300 to 1700h. The resting metabolic rates ofCuetasp.,F. intermediaandPalpares annulatuswere between 5·4–8·9% of the expected values for similar-sized poikilothermic invertebrates. These values indicate low energy demands, which is crucial to survive prolonged periods of starvation.
The non-pitbuilding antlion larva,F. intermedia, was generally more active thanCuetasp., with an unexpectedly high specific metabolic rate for its body size.Furgella intermediahad lower Q10values between 10–30°C than the pitbuilderCuetasp., implying a larger metabolic tolerance to these temperatures.
The increase in metabolism after feeding (ranging between 2·8–3·7 times pre-feeding metabolism) was lowest for the largerP. annulatus, indicating low feeding costs for this species.
Airway epithelium releases inhibitory factors, such as nitric oxide (NO) and prostaglandin E2 (PGE2), which may counteract bronchoconstriction. We investigated whether epithelium-derived inhibitory ...substances exert a crucial influence on bovine tracheal responsiveness in vitro. Isotonic and isometric contractions in response to histamine of intact and epithelium-denuded tracheal smooth muscle strips were compared. In addition, the effects of L-arginine (L-arg), N(G)-nitro-L-arginine methyl esther (L-NAME), and N(G)-monomethyl L-arginine (L-NMMA) on histamine responsiveness were investigated. The release of NO and PGE2 from tracheal epithelium was measured. Removal of the epithelium from tracheal smooth muscle strips did not change the negative log of the concentration of histamine producing half the maximal effect (pD2) or the maximal effect (Emax). Incubation of the tissues for 25 min with L-arg or L-NAME did not influence basal tone or the contractions induced by histamine. However, incubation with L-NMMA increased the basal tone and caused a slight hyporesponsiveness to histamine. S-nitroso-N-acetyl-penicillamine (SNAP, a direct NO donor) reversed the contraction induced by histamine in a concentration-dependent manner. Stimulation of the epithelial layer by 0.1 microM histamine increased the release of NO 3-4 fold compared to basal levels; this effect was completely inhibited in the presence of L-NMMA. In addition, 1 mM histamine caused a significant increase in the release of PGE2 from the epithelial tissue. In conclusion, no functional inhibitory influence of the epithelium can be identified in bovine airways. The S-nitroso-N-acetyl-penicillamine-induced relaxation demonstrates the presence of a nitric oxide sensitive pathway in bovine airways. However, the amounts of nitric oxide and prostaglandin E2 released from bovine tracheal epithelium are probably too low to exert a significant effect on the histamine-induced contractions.
A method for constructing contour maps in disease mapping using smoothing splines is presented. Smoothing errors are discussed and error maps suggested. The approach is illustrated for mortality data ...on cardiovascular diseases in northwestern Germany (Lower Saxony and Bremen) 1970-1979.
Serum TPS, CA 15-3 and CEA levels were measured in 31 women when progressive metastatic disease was established according to UICC criteria. A method was developed to apply these serum tumor markers ...in order to measure the short-term effect of the treatment. Using strict criteria, whereby an increase of the markers of more than 25% indicated progressive disease and a decrease of more than 50% indicated a positive effect of the treatment, TPS (which measures tumoral activity) was shown to be a more sensitive and earlier marker for measuring treatment response than CA 15-3 and CEA (which measure tumor mass).
Prey utilisation at low prey densities was determined for third instar
Cueta sp.,
Furgella intermedia (Markl) and
Palpares annulatus (Stitz) larvae in terms of wet weight, dry weight, energy and ...nutrients. Prey utilisation was similar to other insects on a wet weight (42–47%), dry weight (46–49%), energetic (40–58%) and nutritive basis (62–79%). Lipids (33–36%) provided energetically the highest contribution of the nutrients ingested. The quantities of water, proteins, nucleic acids, lipids and carbohydrates extracted by the antlion larvae were in proportion to their availability in their prey, the
Hodotermes mossambicus larvae. The quantities of nutrients extracted by the antlion larvae at low prey densities were not significantly influenced by the differences in mandible size, antlion body weight or the trapping method (building a pit or not) of the antlion species. It is proposed that a low metabolic rate and the accumulation of fat reserves, and not the extent of prey utilisation, enable
P. annulatus larvae to tolerate a 123-d starvation period in which 22.3% of their body weight is lost.
To determine the geographical distribution and relative abundance of Culicoides species associated with livestock, 220-V down-draught light-traps equipped with 8-W blacklight tubes were operated at ...34 sites in different climatic regions in South Africa and Lesotho. From January 1984 to September 1986, 3 041 631 Culicoides, belonging to at least 50 species, were collected in a total of 959 collections. Of these, 572 412 individuals were identified and sexed. Culicoides species were found to be widespread in South Africa and were collected in varying numbers at all the sites sampled. The average catch size, however, was larger in frost-free areas than in areas with extreme winters. The more abundant and widespread species, which have the potential to be vectors of stock-associated viruses such as bluetongue and African horsesickness, were C. imicola, C. leucostictus, C. schultzei s.l., C. pycnostictus, C. nivosus, C. similis, C. zuluensis, C. magnus, C. bedfordi, C. neavei, C. brucei, C. tropicalis, C. exspectator, C. gulbenkiani, C. bolitinos, C. ravus, C. coarctatus and C. onderstepoortensis. Of these, C. imicola was the most abundant species, being dominant at 17 of the 34 sites sampled and accounting for 71.4% of the specimens collected. As C. imicola is relatively uncommon in hot and dry as well as cool and wet areas, this species cannot be regarded as the only vector of stock-associated viruses in southern Africa. Further laboratory vector-competence studies, i.e. determination of viral-infection and -transmission rates, should first concentrate on the above-mentioned Culicoides species, especially those known to feed on livestock.
The findings in a patient with complete AV block and intra-atrial conduction disturbances due to Lyme disease are presented.
The electrocardiographic follow-up and serial EP findings suggest that ...complete AV block in Lyme disease may signify a more
extensive affection of the AV conduction system (with eventually attendant intra-atrial conduction disturbances) than described
in earlier reports. An almost complete resolution of the considerable damage to the conduction system occurred within two
weeks.
The kinetic constants of human lactate dehydrogenase 1 and 5 (L-lactate: NAD+ oxidoreductase, EC 1.1.1.27), assayed lactate-to-pyruvate increase with temperature. The reaction mechanism is ordered ...sequential as has been found with lactate dehydrogenase from other sources. The KM values for each substrate are larger for isoenzyme 5 than for 1. For lactate dehydrogenase 1 the KM(lactate) increases from 1.07 mM at 25 degrees C to 3.95 mM at 37 degrees C and for lactate dehydrogenase 5 it increases from 5.37 mM at 25 degrees C to 6.88 mM at 37 degrees C. The KM(NAD+) for lactate dehydrogenase 5 is 0.14 mM at 25 degrees C and 0.29 mM at 37 degrees C. The increase in the KM for each substrate with increasing temperature confirms that additional substrate is required for optimal reaction conditions at higher temperatures.
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